A bottle design including a breakaway or twist-off closure which is designed to be grasped by children and which includes a concavo-concave bottom portion is disclosed in U.S. Design Pat. No. 304,683 to Hofer and U.S. Pat. No. 5,076,452 to Hashimoto both of which are hereby incorporated by reference. The commercial embodiments of these patented bottles also includes a concave bottom having a curved rim and indentations therein. Other twist-off caps of general interest are disclosed in the following U.S. Pat. Nos.: 3,356,244 (Witchell), 4,207,990 (Weiler et al.), 4,458,818 (Hansen), and 4,620,638 (Schmidt).
An ornamental design for a combined bottle and breakaway closure is disclosed in U.S. Design Pat. No. 248,827 (Goldschmidt et al.), this bottle including a pleated neck portion. Other designs containing a pleated neck portion are disclosed in U.S. Design Pat. No. 268,810 (Hartung), U.S. Design Pat. No. 245,576 (Muscatiello et al.) and U.S. Design Pat. No. 507,059 (Bostwick et al.). A container with a flexible neck is also disclosed in U.S. Design Pat. No. 301,836 (van Lit).